Monitoring battery charge levels may be done efficiently using a simple circuit that uses flashing LEDs as a battery status indicator.
A BC547 and BC557 transistor are used in this circuit, along with resistors, capacitors, a diode and an LED.
The circuit uses an LED to visually indicate the batteries condition by creating a pattern of flashing lights.
It uses a 6 to 12V battery to run, and it offers a simple and easy way to check the health of the battery and guarantee dependable functioning.
Circuit Working:
Parts List:
| Component | Specification | Quantity |
|---|---|---|
| Resistors | ||
| 120k | 1/4 watt | 1 |
| 5.6k | 1/4 watt | 1 |
| 33k | 1/4 watt | 1 |
| 680k | 1/4 watt | 1 |
| 100k | 1/4 watt | 1 |
| 180Ω | 1/4 watt | 1 |
| 220Ω | 1/4 watt | 2 |
| Preset 4.7k | 1 | |
| Capacitors | ||
| Electrolytic 4.7μF 25V | (kindly note C2 in diagram is also 4.7μF capacitor mistakenly written as 47μF) | 2 |
| Semiconductors | ||
| Transistor BC547 | 1 | |
| Transistor BC557 | 1 | |
| Diode BAT46 | (or any Schottky diode) | 1 |
| LED | 5mm 20mA | 1 |
An LED in this circuit will keep blinking as long as the battery that has to be checked has a voltage higher than the predetermined level.
An astable multivibrator that is complimentary is created by wiring the transistors Q1 and Q2.
The voltage range that the circuit can run on is 6V to 12V.
It is possible to select the voltage level at which the LED must cease flashing by modifying the preset VR1.
The frequency of flashing reduces as the battery voltage approaches the threshold, and the LED turns off when the voltage drops below it.
The diode D1 is employed to offset temperature related variations in Q1s base emitter voltage.
Formulas:
A basic battery status indicator circuit with flashing LEDs would typically make use of the following formulas:
LED Resistor Calculations:
You can use ohms law to figure out the right resistor value for the LED:
R = Vsource−VLED / ILED
where,
- R is the ohms per resistor value
- Vsource is the supply voltage 6 to 12V
- VLED is the LEDs forward voltage 2V for a normal 5mm LED.
- Desired current via the LED 20mA or 0.02A is represented by ILED.
Voltage Divider:
A voltage divider to reduce the battery voltage in order to measure in the circuit diagram R1 and R2, then the formula is:
Vout = Vin× R2 / R1+R2
where,
- Vout is the reduced output voltage
- Vin is the input voltage i.e battery voltage.
- R1 and R2 are the voltage dividers resistor values in the circuit diagram.
These formulas helps in circuit design so that the LED flashes at the appropriate pace and uses the battery voltage appropriately.
How to Build:
To build a Simple Battery Status Indicator Circuit using Flashing LED follow the below mentioned steps for connections:
- Assemble all the required circuit parts as shown in the above diagram.
- Connect collector of transistor Q1 to base of transistor Q2 through resistor R5.
- Connect base of transistor Q1 between resistor R1 and R2 as shown in diagram.
- Connect emitter of Q1 transistor to ground.
- Connect resistor R1, R2, diode D1 and preset VR1 in series from positive supply to ground.
- Connect collector of transistor Q2 to ground through resistor R8 and LED1.
- Connect base of transistor Q2 to collector of transistor Q1.
- Connect emitter of transistor Q2 to positive supply of 6V to 12V power supply.
- Connect resistor R7 between base of transistor Q2 and resistor R5.
- Connect resistor R3 between collector of transistor Q1 and resistor R5.
- Connect capacitor C1 and resistor R4 between resistor R3 and resistor R7.
- Connect capacitor C2 and resistor R6 between collector of Q1 transistor and collector of transistor Q2 and resistor R8
Conclusion:
An easy way to keep an eye on battery levels is using this simple circuit for a battery status indicator that uses a blinking LED.
This technique improves battery management by alerting when replacement or recharging is necessary and is useful for rapid inspections.
It is a useful option for many electrical applications due to its simple design and simple implementation.